The technical field involving the cutting of graphic areas from sheets, or otherwise doing narrow-path-processing about graphics images on sheets, includes, for example, the face-cutting of laminate sheets to form decals. More specifically, a graphic on the face layer of a laminate needs to be cut away from the remainder of the face layer so that the graphic (decal) can subsequently be pulled away from the backing layer of the laminate and be applied elsewhere as intended. Highly accurate face-layer cutting about the graphics is obviously highly desirable.
This is but one example in which highly accurate sheet cutting is desirable. In many other situations, highly accurate sheet cutting may not involve face-cutting, but through-cutting, in which the full thickness of the sheet is cut about a graphic on the sheet. And in many situations, rather than highly accurate cutting, highly accurate scoring, creasing, line embossing or the like, in each case, of course, along a line the varying direction of which is determined by the shape of the graphic. Together these types of operations on sheets with respect to graphics thereon are referred to herein as “narrow-path-processing.” For convenience, the prior art problems and the invention herein which solves such problems will be discussed primarily with reference to sheet-cutting apparatus.
A method and associated apparatus which address many of the problems encountered in such processing of sheet material is the i-cut® vision cuffing system from Mikkelsen Graphic Engineering of Lake Geneva, Wis., and are the subject of a pending U.S. Pat. No. 6,772,661. The invention described in such document is a method and apparatus for achieving highly improved accuracy in cutting around graphics in order to fuiiy adjust for two-dimensional distortion in the sheets from which the graphics will be cut, including distortion of differing degrees in one dimension or along one direction on the sheet of material. The distortion may be from the printing process or from some other post-printing process such as material handling or during the cuffing process itself. This invention also provides improved speed and accuracy in narrow-path-processing and greater efficiency of material usage.
In some cases, such as in the i-cut™ system from Mikkelsen Graphic Engineering, a flatbed plotter is used. These are devices having a positionally-controlled cutting implement above a flat work surface on which the sheet to be cut rests. The cutting implements are controlled based on controller-supplied instructions based on the X-Y coordinates necessary to achieve cutting along the intended path, such as about the graphic.
Achieving greater speed and overall efficiencies in narrow-path-processing is a continuing challenge encountered with such systems. One source of inefficiency is the manual intervention often required to adjust the initial position and alignment of the sheet on the work surface of the cutting apparatus. Sheets of material on which graphics have been previously printed are placed on the work surface of the cutting apparatus, either manually or by automatic sheet-feeding equipment. In either of these set-up situations, the cutting apparatus must determine the position and orientation of the sheet on the work surface in order to proceed accurately with the cutting process. If the operator or automatic sheet-feeder places the sheet of material on the work surface such that it is outside of the area or region of alignment on the work surface which the cutting system expects to find the sheet, manual intervention may be necessary to adjust the placement of the sheet to within the required initial region in order for the process to continue beyond this initial set-up step. Another source of inefficiency is the time-consuming step which may be required to allow the system to determine the initial position and orientation of the sheet on the work surface.
Another source of inefficiency is the requirement that information pertaining to a specific graphic be created and entered into the processing controller. Such information may require additional scanning of each sheet of material on which graphics are applied or otherwise inputting data concerning X-Y positions, angle orientations, scale factors, types or shapes of marks, graphic boundaries, etc.
Another measure of efficiency is the amount of material waste which is produced during narrow-path-processing. Depending on volumes of material processed and the cost of the material used, the amount of waste may be important to minimize in order to increase overall process efficiency.
Despite the significant advances represented by the i-cut™ system, these advances have not yet achieved the highest levels of performance which potentially can be reached by automated cutting systems. Further increases in efficiency (precision, speed and efficiency of operation, and material usage) are highly desirable in automated cutting systems.